In the United States, insurance is regulated by the states under the McCarran-Ferguson Act, with "periodic proposals for federal intervention", and a nonprofit coalition of state insurance agencies called the National Association of Insurance Commissioners works to harmonize the country's different laws and regulations. The National Conference of Insurance Legislators (NCOIL) also works to harmonize the different state laws.
Liability insurance coverage on a personal auto policy follows the driver no matter whose vehicle is being operated, provided it is an eligible vehicle. All states, except for one (New Hampshire), require at least liability coverage. Liability coverage protects the insured (i.e., follows the driver) when the insured operates a vehicle owned by someone else. In such a situation, they will still usually be covered under their own auto insurance policy. However, the best rule of thumb in looking for coverage under a policy is to begin with the exclusions.